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The KAction class (and derived and super classes) provides a way to easily encapsulate a "real" user-selected action or event in your program.
For instance, a user may want to paste
the contents of
the clipboard or scroll
down
a document or @ quit the
application. These are all actions
-- events that the
user causes to happen. The KAction class allows the developer to
deal with these actions in an easy and intuitive manner.
Specifically, the KAction class encapsulated the various attributes
to an event/action. For instance, an action might have an icon
that goes along with it (a clipboard for a "paste" action or
scissors for a "cut" action). The action might have some text to
describe the action. It will certainly have a method or function
that actually executes
the action! All these attributes
are contained within the KAction object.
The advantage of dealing with Actions is that you can manipulate the Action without regard to the GUI representation of it. For instance, in the "normal" way of dealing with actions like "cut", you would manually insert a item for Cut into a menu and a button into a toolbar. If you want to disable the cut action for a moment (maybe nothing is selected), you woud have to hunt down the pointer to the menu item and the toolbar button and disable both individually. Setting the menu item and toolbar item up uses very similar code.. but has to be done twice!
With the Action concept, you simply "plug" the Action into whatever GUI element you want. The KAction class will then take care of correctly defining the menu item (with icons, accelerators, text, etc) or toolbar button.. or whatever. From then on, if you manipulate the Action at all, the effect will propogate through all GUI representations of it. Back to the "cut" example: if you want to disable the Cut Action, you would simply do 'cutAction->setEnabled(false)' and the menuitem and button would instantly be disabled!
This is the biggest advantage to the Action concept -- there is a
one-to-one relationship between the "real" action and all
GUI representations of it.
The steps to using actions are roughly as follows
Here is an example of enabling a "New [document]" action
KAction *newAct = new KAction(i18n("&New"), "filenew", KStdAccel::key(KStdAccel::New), this, SLOT(fileNew()), this); |
This line creates our action. It says that wherever this action is displayed, it will use "&New" as the text, the standard icon, and the standard accelerator. It further says that whenever this action is invoked, it will use the fileNew() slot to execute it.
QPopupMenu *file = new QPopupMenu; newAct->plug(file); |
That just inserted the action into the File menu. You can totally forget about that! In the future, all manipulation of the item is done through the newAct object.
newAct->plug(toolBar()); |
And this inserted the Action into the main toolbar as a button.
That's it!
If you want to disable that action sometime later, you can do so with
newAct->setEnabled(false) |
and both the menuitem in File and the toolbar button will instantly be disabled.
Note: if you are using a "standard" action like "new", "paste", "quit", or any other action described in the KDE UI Standards, please use the methods in the KStdAction class rather then defining your own.
If you are using KAction within the context of the XML menu and toolbar building framework, then there are a few tiny changes. The first is that you must insert your new action into an action collection. The action collection (a KActionCollection) is, logically enough, a central collection of all of the actions defined in your application. The XML UI framework code in KXMLGUI classes needs access to this collection in order to build up the GUI (it's how the builder code knows which actions are valid and which aren't).
Inserting your action into the collection is very simple. To use a previous example:
KAction *newAct = new KAction(i18n("&New"), "filenew", KStdAccel::key(KStdAccel::New), this, SLOT(fileNew()), actionCollection()); |
The only change is to use 'actionCollection()' as the parent of the action. That's it!
Also, if you use the XML builder framework, then you do not ever have to plug your actions into containers manually. The framework does that for you.
|
Construct an action with text and potential keyboard accelerator but nothing else. Use this only if you really know what you are doing.
Parameters:
|
Construct an action with text, potential keyboard accelerator, and a SLOT to call when this action is invoked by the user.
If you do not want or have a keyboard accelerator,
set the accel
param to 0.
This is the most common KAction used when you do not have a corresponding icon.
Parameters:
|
Construct an action with text, icon, and a potential keyboard accelerator.
This Action cannot execute any command. Use this only if you really know what you are doing.
Parameters:
|
Construct an action with text, automatically loaded icon, and a potential keyboard accelerator.
This Action cannot execute any command. Use this only if you really know what you are doing.
Parameters:
|
Construct an action with text, icon, potential keyboard accelerator, and a SLOT to call when this action is invoked by the user.
If you do not want or have a keyboard accelerator, set the
accel
param to 0.
This is the other common KAction used. Use it when you
do
have a corresponding icon.
Parameters:
|
Construct an action with text, icon, potential keyboard accelerator, and a SLOT to call when this action is invoked by the user. The icon is loaded on demand later based on where it is plugged in.
If you do not want or have a keyboard accelerator, set the
accel
param to 0.
This is the other common KAction used. Use it when you
do
have a corresponding icon.
Parameters:
|
Construct a null action.
Parameters:
~ |
[virtual]
Standard destructor
int |
[virtual]
"Plug" or insert this action into a given widget.
This will typically be a menu or a toolbar. From this point on, you will never need to directly manipulate the item in the menu or toolbar. You do all enabling/disabling/manipulation directly with your KAction object.
Parameters:
void |
[virtual]
"Plug" or insert this action into a given KAccel.
It is sometimes useful to use the action paradigm for actions that are not associated with some widget (ie actions that are only activated by keyboard).
Parameters:
void |
[virtual]
"Unplug" or remove this action from a given widget.
This will typically be a menu or a toolbar. This is rarely used in "normal" application. Typically, it would be used if your application has several views or modes, each with a completely different menu structure. If you simply want to disable an action for a given period, use setEnabled() instead.
Parameters:
void |
[virtual]
Disconnect this action from the KAccel.
bool |
[const virtual]
returns whether the action is plugged into any container widget or not.
bool |
[const virtual]
returns whether the action is plugged into the given container with the given, container specific, id (often menu or toolbar id ) .
bool |
[const virtual]
returns whether the action is plugged into the given container with the given, container specific, representative container widget item.
QWidget* |
[const]
int |
[const]
QWidget* |
[const]
int |
[const]
QPixmap |
[const virtual]
bool |
[const virtual]
QString |
[const virtual]
QString |
[const virtual]
Get the text associated with this action.
int |
[const virtual]
Get the keyboard accelerator associated with this action.
bool |
[const virtual]
Returns true if this action is enabled.
QString |
[const virtual]
QString |
[const virtual]
Get the What's this text for the action.
QString |
[const virtual]
Get the tooltip text for the action.
QString |
[const virtual]
QIconSet |
[const virtual]
Get the QIconSet from which the icons used to display this action will be chosen.
QString |
[const virtual]
KActionCollection * |
[const]
int |
[static]
Generate a toolbar button id. Made public for reimplementations.
void |
void |
[virtual slot]
Set the text associated with this action. The text is used for menu and toolbar labels etc.
void |
[virtual slot]
Set the keyboard accelerator associated with this action.
void |
[virtual slot]
void |
[virtual slot]
Set the What's this text for the action. This text will be displayed when a widget that has been created by plugging this action into a container is clicked on in What's this mode.
The What's this text can of course include QML markup as well as raw text.
void |
[virtual slot]
Set the tooltip text for the action.
void |
[virtual slot]
Set the QIconSet from which the icons used to display this action will be chosen.
void |
[virtual slot]
void |
[virtual slot]
void |
[virtual slot]
Enables or disables this action. All uses of this action (eg. in menus or toolbars) will be updated to reflect the state of the action.
void |
[virtual slot]
Emulate user's interaction programmatically, by activating the action. The implementation simply emits activated().
void |
[protected virtual slot]
void |
[protected virtual slot]
void |
[protected virtual slot]
KToolBar* |
[protected const]
QPopupMenu* |
[protected const]
void |
[protected]
int |
[protected const]
void |
[protected]
void |
[protected]
void |
[protected virtual]
void |
[protected virtual]
void |
[protected virtual]
void |
[protected virtual]
void |
[protected virtual]
void |
[protected virtual]
void |
[protected virtual]
void |
[protected virtual]
void |
[protected virtual]
int |
[protected]
for backwards compatibility. depreceated!
KActionCollection * |
[protected]
void |
[signal]
void |
[signal]
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